The present invention relates generally to disposable filters for fluid streams, and more particularly to a filter system employing one or more pre-filters and one or more final filters located downstream of the pre-filters.
Many materials and combinations of materials have been used as filtration media to remove solid or liquid particulate from fluid streams. The capabilities of such filter media are judged according to three main criteria: (1) the particulate removal efficiency (i.e., the ability of the filter media to capture and retain particulate); (2) the pressure drop for a given flow rate of fluid through the media (which is utilized as a measure of the power required to move the fluid stream through the media); and (3) the holding capacity (i.e., the total amount of particulate which can be retained by the media before the pressure drop becomes so great that the media must be cleaned or replaced).
The filter disclosed in the co-pending application is designed to be placed in the fluid stream to trap the particulates suspended in a particulate-laden fluid stream. The cost of the filters disclosed in the co-pending application is not insignificant, so anything that can be done to extend the life thereof will result in a significant cost reduction in the filtering process.
A filter system for filtering particulate material from a generally unidirectional fluid stream is disclosed comprising a first filter removably positioned in the fluid stream and a second filter removably positioned in the fluid stream downstream of the first filter. The first filter is a pre-filter and comprises a layer of fluid-permeable material having an intake side and a discharge side with the layer having a plurality of spaced-apart openings extending completely therethrough. The first and second filters may be either placed adjacent one another in the fluid stream or spaced-apart in the fluid stream. Further, a plurality of first filters may be utilized. Additionally, a plurality of the second filters may be positioned in the fluid stream. The openings extending through the first filter are sufficiently large such that the openings do not plug due to the accumulation of filter particulate. The use of the fluid permeable material in the first filter allows some particulate-laden fluid to pass through the material itself, while some particulate material is filtered by the permeable material in the first filter. The purpose of the first filter being located upstream of the second or normal filter is to reduce the amount of particulate material being presented to the second filter. The presence of the openings in the first filter reduces the amount of raw material required to cover a fluid flow area, therefore enabling the pre-filter to be made less expensively.
It is a principal object of the invention to provide an improved fluid filter system.
Still another object of the invention is to provide a method of filtering particulate material from a generally unidirectional fluid stream.
A further object of the invention is to provide a fluid filter system employing a pre-filter upstream of the normal filter.
Yet another object of the invention is to provide a fluid filter system which employs the use of relatively inexpensive pre-filtering material upstream of the normal filter to extend the life of the normal filter.
Still another object of the invention is to provide a fluid filter system employing a pre-filter which is comprised of a layer of fluid-permeable material having a plurality of spaced-apart openings extending completely therethrough with a reinforcing material being associated therewith to prevent the filter from collapsing or sagging.
These and other objects will be apparent to those skilled in the art.